Battery Dead

[andrew_churcher]

Hi All,

I hope you can help.

My S2 is a weekend car at present. I am finding that if I drive the car on the weekend and dont use it during the week the battery will be flat by Thursday morning. At the moment i have no need and little time to drive it during the week.

Its kept in a underground car park so I cant run a conditioner to it and even if i take the car for a drive during the week it still doesnt guarentee it will start Sat morning. It went flat upteen times during winter.

I am thinking to disconnect the battery during the week as I am sure the immobiliser is draining it while left standing. Does anyone else have to do this? Also how do i check if the battery actually needs to be replaced? Any certain signs that its cactus?

Appreciate the help and sorry for another battery question.

Rgds,

 

[timbership]

Hi Andrew,

I had/have the same problem on my S2 Cabrio, even after fitting a new battery, so I fitted a dis-car-nect bought from ebay. I used to have one on my Lightweight Landrover, but more for security reasons. I haven't had a problem since. I disconnect the battery by turning the thumbwheel and then manually lock the doors. If I lock the doors first then the alarm goes of when I reconnect the battery. This does, however raise the issue of deliberately disarming the car's alarm system, I don't have a problem with it, but I'm sure my insurance company might! Also, other posters on this forum have had issues of gaining entry when the battery goes flat, my key manually operates the locks so this hasn't been an issue, I presume you can do the same? With the battery in the boot I don't find it any hassle to do and do it whenever I park the car. The dash clock of course would need resetting every time, but since the LCD on mine has bled, I can't see it anyway.

 

[zcacogp]

Two useful tests.

1. Test the discharge of the battery when shorted across a load. This will need to be done by a garage, but takes seconds and tells you how knackered the battery is.

2. Wire an ammeter between the battery and the car and see how much current the immobiliser is taking. Do some maths and work out how many hours the battery should be able to run the immobiliser before it's completely flat. If the alarm/immob current drain is too high then the battery will be flat sooner (clearly!)

My experience of alarms and immobilisers is that when re-connected they immediately go into the 'immobilised' state, as a theft precaution. On this basis I don't see how the insurance company could object.


Oli.

 

[zcacogp]

ORIGINAL: sc0tty
96Ah I think

Flip me - that's a biggun!

Porsche specify a 65 (minimum). My last one was a 45.

I'm surprised a 96 fits in the space in the boot!


Oli.

 

[944Fripp]

I've got the same BOSCH battery in mine. It used to be pretty sluggish on start up especially when it was cold recently but since fitting the new battery it has no problems at all. Even keeps the cassette player working during start!! []

 

[944 man]

ORIGINAL: sc0tty

Andrew, like you I dont often drive my car during the week either. I have bought a very high amp hour (96Ah I think) bosch silver battery, and it always starts my car week on week.  

This is a nice battery, but if you have an excessive current drain then itll probably not help. In order to deal with the problem you have to identify it. In order identify the problem you need to know where the problem lies and for this Id suggest that you buy a tester like this. With the ignition off you should be able to identify which circuit or circuits are still drawing current - this will be the cause of your problem.

It could very well be your alarm or immobiliser and the ony recourse may be to disconnect the battery (if James's lorry battery wont work). Alternatively it may be a leak to earth or something staying on that shouldnt be...


Simon

 

[ukmastiff]

I totally agree with much of what has been posted but I would say , before looking for the less commn causes rule out the battery being old and tired.
Quite simply an old and knackered battery is the most common , then the alternator or a curent drain after that. Get your battery checked or even just buy a good strong new one as mentioned. Whatever turns out to be wrong, a strong battery will be a good investment and not wasted cash

Good luck

 

[zcacogp]

That's a useful looking tool Simon. Never seen anything like that before, but I have made a similar one out of an old fuse. Cut the plastic back to get to the back of the spade connections, and then solder a lead onto each of them. You can then connect these leads to your regular ammeter, which will display the current being drawn by that particular circuit. Having said that, I think my ammeter only reads up to 1a, and that tool says it goes up to 20a. Handy.

Mas, I disagree. New batteries start at around £55 (what I paid for mine last month). And I only replaced it when I was sure it was the fault. Fifty five big ones is a lot of money to spend on spec, and replacing parts without being sure they are at fault is poor diagnostics. Yes, if your battery is 4+ years old and it's coming up to winter then you may want to consider replacing it as a precaution, but that's a slightly different matter. If you really are thinking it could be the battery but aren't sure then hook up some jump leads to another car (while it is running) and see whether that solves the problem.


Oli.

 

[Copperman05]

The batteries do seem to be a bit of an achilles heel on these cars. Therefore it does seem prudent to look after them over the winter months especially as this is often when they are not being regularly used and many of you have second cars.
TBO if left to drain a few times during the very cold weather as we have had this winter I would think most batteries will never perform the same again (batteries hate cold and being discharged, have both and it often ruins them).

Therefore during such times I would disconnect the battery and leave on charge until the next time to use it comes again. Otherwise you may find you are replacing your battery more often than you would like...

Edd

 

[craig2105]

Correct me if I am wrong here, but if you install one of those dis-car-nect things, the device is hidden and so the average thief won't find or have time to do anything about breaching the electrical disconnect before making off with your P&J? However, it's not unknown for cars to be just lifted or towed so maybe the insurance company would have something to say if it was subsequently discovered that the battery was disconnected? But then again, could an insurance company have something to say if your alarm wasn't functioning as a result of a dead battery?

 

[ukmastiff]

You're welcome to disagree of course OLI. But you just said exactly what I'mm on about

" Yes, if your battery is 4+ years old and it's coming up to winter then you may want to consider replacing it as a precaution, but that's a slightly different matter " . Im not suggesting replace a new battery of course but how many folk have a 5 or 10 year old battery plus in there 944 ? , thats what im talking about. I'd change an 'old one' anyway in this situation but thats just me []

Mas

 

[zcacogp]

Fair cop Mas, just that I thought you were suggesting changing a battery as part of a diagnostic process, which I wouldn't agree with.


Oli.

ETA: 10 year old battery in a 944? I don't believe it!

 

[peanut]

there is clearly something wrong with either your battery or your vehicle electrics or both. Most of us leave our cars for extended periods particularly in the winter ,without any restarting problems.
I would suspect that you have a current drain.
A quick and dirty way of checking for a likely culpret is with the ignition off,
Remove the earth terminal from the battery.
Remove all the fuses.
Reinstate one fuse at a time and then connect the earth lead.

If there is a drain on that particular fused circuit you will notice a slight arcing on the battery terminal as you replace the lead due to the current being drawn .
It will take a while but will tell you exactly which circuit is draining your battery.

You can then leave that fuse out to prevent battery drain whilst you sort the problem